A vacuum pumping system and a tube sealing machine having the same

Abstract

The present invention discloses a vacuum pumping system and a tube sealing machine having the same, relating to the technical field of vacuum quartz tube sealing machines, including a molecular pump unit. The molecular pump unit includes a molecular pump and a backing pump. An isolation valve is arranged between the molecular pump and the backing pump. The isolation valve includes a housing. An air inlet pipe and an air outlet pipe are arranged on the housing, and a one-way component is arranged in the air outlet pipe. Through the settings of a fixing cylinder, a baffle plate, a first elastic member, an annular plate, etc., when the backing pump has a decrease in pump pressure, a power outage, or a failure, most of the reflux gas is blocked outside the fixing cylinder, and only a small amount of gas enters the interior of the fixing cylinder. At the same time, the baffle plate quickly contacts the sealing plate under the action of the first elastic member, and the gas entering the fixing cylinder generates a positive push on the baffle plate, making the response speed of the baffle plate faster, thereby reducing or even avoiding the influence of the reflux gas on the molecular pump and improving the response speed of the isolation valve.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum quartz tube sealing machines, and particularly to a vacuum pumping system and a tube sealing machine having the same. Background Art

[0002] A vacuum quartz tube sealing machine is a device specifically used for vacuum packaging of quartz tubes, which can ensure that the air or other gases in the quartz tube are pumped out without introducing impurities and the quartz tube is sealed under a vacuum state. It mainly consists of a vacuum system, a heating system, a cooling system, a support and positioning system, a control system, etc. Among them, the vacuum system includes components such as a fore pump, a molecular pump, a vacuum gauge, and valves.

[0003] Due to the limitations of the molecular pump, it needs to be used in cooperation with the fore pump during the vacuum pumping operation; at the same time, an isolation valve (also called a fore valve) needs to be set between the molecular pump and the fore pump to avoid the fore pump and the molecular pump being separated in time when there is a power outage or a failure, preventing the molecular pump from being impacted by air pressure and gas pollution.

[0004] If the fore pump fails to effectively reduce the pressure, resulting in too large a gas flow rate entering the molecular pump, it may cause the efficiency of the molecular pump to decrease or even fail to work properly. In addition, if the fore pump fails to maintain a sufficient pumping rate, there may be diffusion of oil vapor or other pollutants from the low-vacuum side to the high-vacuum side, causing pollution.

[0005] Chinese Patent with application number 202110484899.9 discloses an automatically opening and closing differential pressure valve for preventing backflow of the fore pump of a molecular pump. Although this invention realizes the automatic opening and closing of the valve through gas differential pressure, cuts off the connection between the fore vacuum and the molecular pump when the fore vacuum pump fails and the vacuum deteriorates, prevents the impact of the fore high air pressure on the blades of the molecular pump, and avoids gas pollution to the vacuum chamber. However, it at least still has the following problems:

[0006] In the actual use process, the opening and closing module has a long response time when moving upward and low sensitivity. Therefore, during this process, there is still a large amount of gas entering the molecular pump through this differential pressure valve, resulting in problems such as an unsatisfactory effect of preventing gas backflow.

[0007] In addition, although existing molecular pump units usually set up a filtering component to filter pollutants such as impurities carried in the backflow gas, the isolation valve itself does not have this function. When the filtering accuracy of the filtering component decreases, the isolation valve cannot perform additional gas filtration, making the vacuum system lack corresponding emergency remedial measures.

[0008] Therefore, the present invention proposes a vacuum pumping system and a tube sealing machine having the same to solve the above problems. Summary of the Invention

[0009] The object of the present invention is to provide a vacuum pumping system and a tube sealing machine having the same, so as to solve the technical problems of slow response speed of the isolation valve and lack of emergency measures for gas filtration proposed in the above background technology.

[0010] To achieve the above object, the present invention provides the following technical solution: a vacuum pumping system, including a molecular pump unit, the molecular pump unit includes a molecular pump and a backing pump, and an isolation valve is arranged between the molecular pump and the backing pump;

[0011] The isolation valve includes a housing, an air inlet pipe and an air outlet pipe are arranged on the housing, the air inlet pipe is connected to the exhaust end of the molecular pump through a pipeline, the air outlet pipe is connected to the air inlet end of the backing pump through a pipeline, a seal is arranged on the top of the housing, a knob is arranged on the seal, a cavity is formed between the seal and the housing, a piston column coaxially arranged is slidably arranged in the cavity, the piston column divides the cavity into an active cavity and a back pressure cavity, air holes are formed through the circumferential side of the piston column, a bypass pipe communicating with the back pressure cavity is arranged on the side wall of the air outlet pipe, and a one-way component is arranged in the air outlet pipe, and the one-way component is located between the piston column and the bypass pipe.

[0012] Preferably, the one-way component includes a fixed cylinder coaxially arranged in the air outlet pipe, the fixed cylinder is a cylindrical structure with both ends open, and the fixed cylinder includes a horizontal section and an inclined section, the cross-sectional diameter of the inclined section of the fixed cylinder changes in a stepped manner along the length direction of the air outlet pipe, one end of the fixed cylinder close to the piston column is the air inlet end, the other end is the air outlet end, and the diameter of the air inlet end is larger than that of the air outlet end.

[0013] Preferably, an annular seal plate is coaxially fixed on the inner wall of the air inlet end, a baffle is coaxially arranged on one side of the seal plate, the baffle moves in the horizontal section of the fixed cylinder, an annular plate is fixedly connected to the inner wall of the fixed cylinder, and a first elastic member is arranged between the baffle and the annular plate.

[0014] Preferably, a rotating cylinder is rotatably connected to the outer wall of the fixed cylinder, a plurality of first through holes and second through holes are respectively formed in the circumferential sides of the fixed cylinder and the rotating cylinder, and the first through holes and the second through holes are arranged in a staggered manner, a connecting rod is coaxially arranged on the baffle, a connecting hole matching the connecting rod is formed at one end of the rotating cylinder, a spiral track is formed on the circumferential side of the connecting rod, and a connecting block matching the spiral track is fixedly connected to the inner wall of the connecting hole.

[0015] Preferably, a filter screen is arranged on the outer wall of the circumferential side of the fixed cylinder.

[0016] Preferably, an adjusting column that slides up and down is arranged in the movable cavity. An adjusting plate is coaxially fixed to the bottom end of the adjusting column in the movable cavity. A second elastic member is arranged between the adjusting plate and the piston column. An air groove is penetratingly formed in the adjusting plate. An adjusting bolt is coaxially fixed to the knob. One end of the adjusting column away from the adjusting plate is in threaded connection with the adjusting bolt. A limiting block is arranged on the circumferential side of the adjusting column. A limiting groove matching the limiting block is formed on the inner wall of the seal.

[0017] Preferably, the seal includes a sealing gasket coaxially arranged on the housing. A sealing sleeve is arranged above the sealing gasket. The adjusting column is in sealed sliding connection with the sealing sleeve. The knob is rotatably connected to the top of the sealing sleeve.

[0018] Preferably, the molecular pump unit further includes a control box, and a control unit is arranged in the control box.

[0019] The present invention also provides a tube sealing machine, which includes the above-mentioned vacuum pumping system and a tube sealing machine main body. The tube sealing machine main body includes a workbench and an operating platform located on one side of the top of the workbench. The molecular pump unit is located in the operating platform, and a control panel is arranged on the operating platform. The control panel is electrically connected to the control box.

[0020] Preferably, a tube sealing assembly is arranged on the workbench. The tube sealing assembly includes a clamping member and a heating member.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. Through the settings of the fixed cylinder, the baffle, the first elastic member, the annular plate, etc., when the pump pressure of the front-stage pump drops, a power failure occurs, or a fault occurs, most of the reflux gas is blocked outside the fixed cylinder, and only a small amount of gas enters the inside of the fixed cylinder. At the same time, the baffle quickly contacts the sealing plate under the action of the first elastic member. The gas entering the fixed cylinder generates a positive push on the baffle, making the response speed of the baffle faster, thereby reducing or even avoiding the influence of the reflux gas on the molecular pump and improving the response speed of the isolation valve.

[0023] 2. Through the settings of the connecting rod, the spiral track, the connecting block, the rotating cylinder, etc., when the baffle is in the open state, the first through hole is communicated with the second through hole, thereby increasing the flow rate of the gas passing through the one-way assembly. This not only avoids the large noise generated by the acceleration of the gas, but also reduces the wear of the fixed cylinder. When used in the laboratory, it can effectively reduce the influence of the noise on the staff, and also extends the service life of the one-way assembly and reduces the maintenance burden of the staff.

[0024] 3. Through the settings of the baffle plate, rotating cylinder and filter screen, etc., in the present invention, if the filtration accuracy of the filter element in the molecular pump unit decreases, when the backflow gas passes through the one-way component, the filter screen can secondary-filter the oil vapor and other pollutants in the gas, preventing these pollutants from damaging the vacuum chamber of the molecular pump, so that the isolation valve has an effective emergency remedy measure; in addition, during each rotation of the rotating cylinder and the opening of the baffle plate, the inner wall of the rotating cylinder and the gas ejected after the baffle plate is opened will clean the filter screen, extending the service life of the filter screen and improving the universality and reliability of the one-way component. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 FIG. is a schematic diagram of the overall structure of a vacuum pumping system and a sealing machine having the same according to the present invention.

[0026] Figure 2 FIG. is a schematic diagram of the structure of the molecular pump unit of the present invention.

[0027] Figure 3 FIG. is a schematic diagram of the structure of the isolation valve of the present invention.

[0028] Figure 4 FIG. is a schematic plan sectional view of the isolation valve of the present invention in a closed state.

[0029] Figure 5 FIG. is a schematic plan sectional view of the isolation valve of the present invention in a conducting state.

[0030] Figure 6 FIG. is a three-dimensional structure schematic diagram of the one-way component of the present invention.

[0031] Figure 7 FIG. is a schematic plan sectional view of the fixed cylinder of the present invention.

[0032] Figure 8 FIG. is an exploded schematic diagram of the one-way component of the present invention.

[0033] Figure 9 FIG. is a schematic plan sectional view of the one-way component of the present invention in a closed state.

[0034] Figure 10 FIG. is a schematic plan sectional view of the one-way component of the present invention in a conducting state.

[0035] Figure 11 FIG. is a schematic diagram of the structure of the spiral track of the present invention.

[0036] Reference numerals are:

[0037] 1. Sealing machine main body; 11. Workbench; 12. Operating table;

[0038] 2. Molecular pump unit; 21. Molecular pump; 22. Fore pump; 23. Control box;

[0039] 3. Isolation valve; 301. Movable chamber; 302. Back pressure chamber; 31. Housing; 32. Inlet pipe; 33. Outlet pipe; 34. Sealing member; 341. Sealing gasket; 342. Sealing sleeve; 35. Knob; 36. Piston rod; 361. Air hole; 37. Bypass pipe;

[0040] 4. One-way component; 41. Fixed cylinder; 411. First through hole; 42. Sealing plate; 43. Baffle; 44. Annular plate; 45. First elastic member; 46. Rotating cylinder; 461. Second through hole; 462. Connecting hole; 47. Connecting rod; 471. Spiral track;

[0041] 5. Adjusting column; 51. Adjusting plate; 52. Second elastic member;

[0042] 6. Adjusting bolt;

[0043] 7. Filter screen. Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0045] Embodiment 1

[0046] During the actual production process, due to the limitations of the molecular pump, a fore pump needs to be used in combination during the vacuum pumping operation; at the same time, an isolation valve needs to be provided between the molecular pump and the fore pump to avoid the situation where when the fore pump has a power outage or a failure, the fore pump and the molecular pump can be separated in time to prevent the molecular pump from being affected by gas pressure shock and gas pollution; and the sensitivity of the existing isolation valve is relatively low, and there are still a large amount of gases passing through the isolation valve and entering the molecular pump during the process of preventing gas backflow; in order to solve the above problems, this embodiment is specifically invented.

[0047] Please refer to Figures 1 to 11 As shown in the figure, a vacuum pumping system according to an embodiment of the present invention includes a molecular pump unit 2, the molecular pump unit 2 includes a molecular pump 21 and a fore pump 22, and an isolation valve 3 is provided between the molecular pump 21 and the fore pump 22.

[0048] Please refer to Figures 3 to 5As shown, the isolation valve 3 includes a housing 31. An air inlet pipe 32 and an air outlet pipe 33 are provided on the housing 31. The air inlet pipe 32 is connected to the exhaust end of the molecular pump 21 through a pipeline, and the air outlet pipe 33 is connected to the intake end of the backing pump 22 through a pipeline. A seal 34 is provided at the top of the housing 31, and a knob 35 is provided on the seal 34. A cavity is formed between the seal 34 and the housing 31. A piston column 36 is slidably arranged in the cavity coaxially. The piston column 36 divides the cavity into an active cavity 301 and a back pressure cavity 302. Air holes 361 are formed through the circumferential side of the piston column 36. A bypass pipe 37 communicating with the back pressure cavity 302 is provided on the side wall of the air outlet pipe 33. A one-way component 4 is arranged in the air outlet pipe 33, and the one-way component 4 is located between the piston column 36 and the bypass pipe 37.

[0049] Please refer to Figure 6 and Figure 7 As shown, the one-way component 4 includes a fixed cylinder 41 coaxially arranged in the air outlet pipe 33. The fixed cylinder 41 is a cylindrical structure with both ends open, and the fixed cylinder 41 includes a horizontal section and an inclined section. The cross-sectional diameter of the inclined section of the fixed cylinder 41 changes stepwise along the length direction of the air outlet pipe 33. One end of the fixed cylinder 41 close to the piston column 36 is the intake end, and the other end is the outlet end, and the diameter of the intake end is larger than that of the outlet end.

[0050] Please refer to Figure 7 As shown, an annular sealing plate 42 is coaxially fixed on the inner wall of the intake end. A baffle 43 is coaxially arranged on one side of the sealing plate 42. The baffle 43 moves in the horizontal section of the fixed cylinder 41. An annular plate 44 is fixedly connected to the inner wall of the fixed cylinder 41. A first elastic member 45 is arranged between the baffle 43 and the annular plate 44.

[0051] Please refer to Figure 4 and Figure 5 As shown, an adjusting column 5 that slides up and down is arranged in the active cavity 301. An adjusting plate 51 is coaxially fixed at the bottom end of the adjusting column 5 in the active cavity 301. A second elastic member 52 is arranged between the adjusting plate 51 and the piston column 36. Air grooves are formed through the adjusting plate 51. An adjusting bolt 6 is coaxially fixed on the knob 35. One end of the adjusting column 5 away from the adjusting plate 51 is threadedly connected to the adjusting bolt 6. A limiting block is arranged on the circumferential side of the adjusting column 5. A limiting groove matching the limiting block is formed on the inner wall of the seal 34.

[0052] Please refer to Figure 4 and Figure 5 As shown, the seal 34 includes a sealing gasket 341 coaxially arranged on the housing 31. A sealing sleeve 342 is arranged above the sealing gasket 341. The adjusting column 5 is in sealed sliding connection with the sealing sleeve 342. The knob 35 is rotatably connected to the top of the sealing sleeve 342.

[0053] Please refer to Figure 2As shown, the molecular pump unit 2 further includes a control box 23, and a control unit is provided inside the control box 23.

[0054] During use, when workers seal the quartz tube, they send an electrical signal to the control box 23 through the control panel on the operation console 12. The fore pump 22 starts. During the process of evacuating, the air pressure in the back pressure chamber 302 drops rapidly. The piston column 36 moves downward under the action of negative pressure, and the air hole 361 gradually communicates with the intake pipe 32 and the outlet pipe 33. As the fore pump 22 continues to work, the baffle 43 moves away from the sealing plate 42 against the elastic force of the first elastic member 45. At this time, the one-way assembly 4 is in a conducting state. The gas at the exhaust end of the molecular pump 21 enters the fore pump 22 through the intake pipe 32, the air hole 361, the one-way assembly 4 and the outlet pipe 33, and is discharged by the fore pump 22.

[0055] When a power outage or a fault occurs in the fore pump 22, a reverse flow phenomenon occurs, that is, the gas moves from the suction end of the fore pump 22 towards the molecular pump 21. Due to the tapered setting of the fixed cylinder 41, only a part of the reverse-flow gas enters the inside of the fixed cylinder 41. After this part of the gas enters the fixed cylinder 41, the baffle 43 quickly fits against the sealing plate 42 under the action of the first elastic member 45 to form a seal. Most of the reverse-flow gas is blocked in the outlet pipe 33 by the one-way assembly 4. At the same time, the pressure in the back pressure chamber 302 gradually increases, and the piston column 36 moves upward under the push of the gas until the air hole 361 is completely sealed.

[0056] Through the settings of the fixed cylinder 41, the baffle 43, the first elastic member 45 and the annular plate 44, etc., when the pump pressure of the fore pump 22 drops, a power outage or a fault occurs, most of the reverse-flow gas is blocked outside the fixed cylinder 41, and only a small part of the gas enters the inside of the fixed cylinder 41. At the same time, the baffle 43 quickly contacts the sealing plate 42 under the action of the first elastic member 45. The gas entering the fixed cylinder 41 produces a positive push on the movement of the baffle 43, making the response speed of the baffle 43 faster, thereby reducing or even avoiding the influence of the reverse-flow gas on the molecular pump 21 and improving the response speed of the isolation valve 3.

[0057] Embodiment 2

[0058] It is found in actual use that when the gas moves from the molecular pump 21 to the fore pump 22, due to the small diameter of the outlet end of the fixed cylinder 41, there will not only be a large noise when the gas passes through, but also the wear of the outlet end will be accelerated during long-term use; further improvements are made on the basis of the above embodiment.

[0059] Please refer to Figures 8 to 11As shown in the figure, a rotating cylinder 46 is rotatably connected to the outer wall of the fixed cylinder 41. A plurality of first through holes 411 and second through holes 461 that are circumferentially evenly distributed are respectively formed on the circumferential sides of the fixed cylinder 41 and the rotating cylinder 46, and the first through holes 411 and the second through holes 461 are arranged in a staggered manner. A connecting rod 47 is coaxially arranged on the baffle 43. A connecting hole 462 that matches the connecting rod 47 is formed at one end of the rotating cylinder 46. A spiral track 471 is formed on the circumferential side of the connecting rod 47, and a connecting block that matches the spiral track 471 is fixedly connected to the inner wall of the connecting hole 462.

[0060] During use, when the baffle 43 moves towards the outlet end under the push of gas, the connecting rod 47 generates an axial movement, and makes the rotating cylinder 46 rotate by a certain angle under the action of the connecting block and the spiral track 471, and the first through holes 411 on the fixed cylinder 41 communicate with the second through holes 461 on the rotating cylinder 46.

[0061] When the gas flows back, the baffle 43 is quickly resealed with the sealing plate 42 under the action of the first elastic member 45, the connecting rod 47 makes an axial movement again, and makes the rotating cylinder 46 reset. At this time, the first through holes 411 and the second through holes 461 become staggered again.

[0062] At the same time, since the response speed of the baffle 43 is relatively fast, even if some gas enters the inside of the fixed cylinder 41 through the second through holes 461 and the second through holes 461 at the initial stage of the backflow, it will not overly affect the anti-backflow effect of the isolation valve 3.

[0063] Through the settings of the connecting rod 47, the spiral track 471, the connecting block and the rotating cylinder 46, etc., when the baffle 43 is in the open state, the first through holes 411 communicate with the second through holes 461, so as to increase the flow rate of gas passing through the one-way component 4, avoid the generation of relatively large noise due to the acceleration of the gas, and reduce the wear of the fixed cylinder 41. When used in the laboratory, it can effectively avoid the influence of noise on the staff, also extend the service life of the one-way component 4, and reduce the labor intensity of the staff.

[0064] Embodiment III

[0065] Although the existing molecular pump unit 2 is provided with a filter element to filter pollutants such as impurities carried in the backflow gas, the isolation valve 3 does not have this function. When the filtering accuracy of the filter element decreases, the isolation valve 3 cannot filter the gas, resulting in a lack of corresponding emergency remedies for the vacuum system. In order to further enhance the filtering effect of the isolation valve 3 on the gas.

[0066] Please refer to Figure 9 and Figure 10 As shown in the figure, a filter screen 7 is arranged on the outer wall of the circumferential side of the fixed cylinder 41.

[0067] During use, when the gas passes through the one-way component 4, the oil vapor and pollutants carried inside it will be filtered out by the filter screen 7, preventing these pollutants from entering the vacuum chamber of the molecular pump 21. At the same time, every time the rotating cylinder 46 rotates once, the rotating cylinder 46 will clean the surface of the filter screen 7.

[0068] At the same time, during the opening process of the baffle 43, the gas pressure entering the fixed cylinder 41 is relatively high and the flow rate is relatively fast. After the gas passes through the first through-hole 411, it will impact the filter screen 7, thereby cleaning the filter screen 7, further improving the use effect of the filter screen 7. At the same time, impurities and other pollutants in the second through-hole 461 will also be washed away under the action of the gas.

[0069] Through the settings of the baffle 43, the rotating cylinder 46, and the filter screen 7, if the filtration accuracy of the filter element set in the molecular pump unit 2 decreases, when the reflux gas passes through the one-way component 4, the filter screen 7 will perform secondary filtration on the oil vapor and pollutants in the gas, preventing the pollutants from damaging the vacuum chamber of the molecular pump 21, enabling the isolation valve 3 to have an effective emergency remedial measure; at the same time, every time the rotating cylinder 46 rotates and during the opening process of the baffle 43, the inner wall of the rotating cylinder 46 and the gas ejected after the baffle 43 is opened will clean the filter screen 7, extending the service life of the filter screen 7 and improving the universality of the one-way component 4.

[0070] Embodiment 4

[0071] Please refer to Figure 1 As shown in the figure, the present invention also provides a tube sealing machine, which includes the above-mentioned vacuum pumping system, including a tube sealing machine main body 1. The tube sealing machine main body 1 includes a workbench 11 and an operating table 12 located on one side of the top of the workbench 11. The molecular pump unit 2 is located inside the operating table 12, and a control panel is provided on the operating table 12. The control panel is electrically connected to the control box 23.

[0072] Please refer to Figure 1 As shown in the figure, a tube sealing component is provided on the workbench 11. The tube sealing component includes a clamping member and a heating member. The clamping member is used to fix the quartz tube to be processed to ensure its correct position during the tube sealing process. The heating member includes a hydrogen-oxygen machine and a spray gun. The spray gun surrounds the sealing position of the quartz tube and softens the quartz material by heating for sealing operation. The clamping member and the heating member are both prior arts and will not be elaborated here.

[0073] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A vacuum pumping system, comprising a molecular pump unit (2), characterized in that: The molecular pump unit (2) comprises a molecular pump (21) and a front-stage pump (22), and an isolation valve (3) is provided between the molecular pump (21) and the front-stage pump (22); The isolation valve (3) comprises a housing (31), the housing (31) being provided with an air inlet pipe (32) and an air outlet pipe (33), the air inlet pipe (32) being connected to the exhaust end of the molecular pump (21) via a pipe, the air outlet pipe (33) being connected to the air inlet end of the fore pump (22) via a pipe, a sealing member (34) being provided at the top of the housing (31), a knob (35) being provided on the sealing member (34), and a cavity being formed between the sealing member (34) and the housing (31), A piston column (36) is coaxially arranged in the cavity for sliding movement, and the piston column (36) divides the cavity into an active cavity (301) and a back pressure cavity (302). An air hole (361) is provided through the circumferential side of the piston column (36). A bypass pipe (37) communicating with the back pressure cavity (302) is provided on the side wall of the air outlet pipe (33). A one-way component (4) is provided in the air outlet pipe (33), and the one-way component (4) is located between the piston column (36) and the bypass pipe (37). The one-way component (4) comprises a fixing cylinder (41) coaxially arranged in the air outlet pipe (33); The fixed cylinder (41) is a cylindrical structure with two ends open, and the fixed cylinder (41) comprises a horizontal section and an inclined section, the cross-sectional diameter of the inclined section of the fixed cylinder (41) changes in a step-like manner along the length direction of the outlet pipe (33), one end of the fixed cylinder (41) close to the piston rod (36) is an air inlet end, and the other end is an air outlet end, and the diameter of the air inlet end is greater than the diameter of the air outlet end; An annular sealing plate (42) is coaxially fixed on the inner wall of the air inlet end, and a baffle (43) is coaxially arranged on one side of the sealing plate (42); A rotating cylinder (46) is rotatably connected to the outer wall of the fixed cylinder (41); a plurality of first through holes (411) and second through holes (461) evenly distributed around the circumference are respectively provided on the circumferential sides of the fixed cylinder (41) and the rotating cylinder (46); the first through holes (411) and the second through holes (461) are arranged in a staggered manner; a connecting rod (47) is coaxially arranged on the baffle plate (43); a connecting hole (462) matching the connecting rod (47) is provided at one end of the rotating cylinder (46); a spiral track (471) is provided on the circumferential side of the connecting rod (47); and a connecting block matching the spiral track (471) is fixedly connected to the inner wall of the connecting hole (462).

2. A vacuum pumping system according to claim 1, characterized in that: The baffle plate (43) moves in the horizontal section of the fixed cylinder (41); an annular plate (44) is fixedly connected to the inner wall of the fixed cylinder (41); and a first elastic member (45) is provided between the baffle plate (43) and the annular plate (44).

3. A vacuum pumping system according to claim 2, characterized in that: A filter screen (7) is provided on the outer wall of the circumferential side of the fixed cylinder (41).

4. A vacuum pumping system according to claim 3, characterized in that: An adjusting column (5) that slides up and down is arranged in the movable cavity (301); an adjusting plate (51) is coaxially fixed to one end of the adjusting column (5) located in the movable cavity (301); a second elastic member (52) is arranged between the adjusting plate (51) and the piston column (36); an air groove is provided through the adjusting plate (51); an adjusting bolt (6) is coaxially fixed to the knob (35); an end of the adjusting column (5) away from the adjusting plate (51) is threadedly connected to the adjusting bolt (6); a limiting block is arranged on the circumferential side of the adjusting column (5); and a limiting groove matching the limiting block is arranged on the inner wall of the sealing member (34).

5. A vacuum pumping system according to claim 4, characterized in that: The sealing member (34) comprises a sealing gasket (341) coaxially arranged on the housing (31), a sealing sleeve (342) is arranged above the sealing gasket (341), the adjusting column (5) is sealingly and slidably connected to the sealing sleeve (342), and the knob (35) is rotatably connected to the top of the sealing sleeve (342).

6. A vacuum pumping system according to claim 5, characterized in that: The molecular pump unit (2) further comprises a control box (23), wherein a control unit is arranged in the control box (23).

7. A tube sealing machine, characterized in that: A vacuum pumping system according to any one of claims 1 to 6, comprising a tube sealing machine body (1), wherein the tube sealing machine body (1) comprises a workbench (11) and an operating table (12) located on one side of the top of the workbench (11), wherein the molecular pump unit (2) is located in the operating table (12), and a control panel is provided on the operating table (12), and the control panel is electrically connected to a control box (23).

8. A tube sealing machine according to claim 7, characterized in that: A tube sealing assembly is arranged on the workbench (11), and the tube sealing assembly comprises a clamping element and a heating element.

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